Agricultural chemicals are usually distributed in mixtures or blends that may include solvents, promoters, adjuvants, surfactants, emulsifiers, and the like. Many are distributed in liquid emulsifiable concentrates which are blended with water at the treatment site to produce an emulsion that is distributed over crops. The emulsion provides a vehicle for the chemical phase to contact plant surfaces to deliver the agricultural chemical efficiently. Other formulation types include water-based emulsions, suspoemulsions, and microemulsifiable concentrates.
It is generally desired that the chemical formulation contact and cover plant surfaces efficiently and be relatively resistant to water dissolution, such that the chemicals remain in effective contact with the plants and do not merge with ground water. It is also desired that any chemicals that do merge with ground water have low water toxicity.
The use of solvents in the preparation of agricultural chemical formulations is well known. Agricultural active components are often solids or oily liquids that must be brought into aqueous suspension for final use. These active components are typically first dissolved in a water immiscible solvent. Organic solvents have been used in various formulation types since the 1950's when pesticide products were first developed and used on a large scale. Commonly used solvents include alkyl benzenes, methyl esters of fatty acids, aliphatic and cycloaliphatic hydrocarbons, and fuel oils, all of which have low water solubility but relatively low solvating power. The organic solvents often have significant toxicity, and may be flammable.
Solvents showing reduced toxicity and/or flammability that have been used include dibasic esters, usually methyl esters, of C8-C16 dicarboxylic acids, fatty acid amide solvents such as dimethylamide and morpholineamide derivatives of C6-C16 fatty acids, and mono-alkylene carbonates such as ethylene carbonate, propylene carbonate and butylene carbonate. These solvents have limited solvating power with respect to the active components, however, are expensive to purify, and some have substantial solubility in water.
Other solvents include isophorone, MEK, n-methylpyrolidone, butyl lactate, DMSO, and acetophenone, all of which are good solvents but also have undesirable water solubility. There is a continuing need for agricultural chemical formulations using solvents with low odor, toxicity, and water solubility, but good solvating power with respect to agricultural chemicals.